NES 2.0 Mapper 447

NES 2.0 Mapper 447 denotes the VRC4-based KL-06 multicart circuit board used by the 1993 New 860-in-1 Over-Valued Golden Version Games multicart. The VRC4 clone's A0/A1 inputs are connected to CPU A2/A3, and its PRG-RAM chip-enable signal drives an outer bank register.

Outer Bank Register ($6000-$7FFF, write)

A~[0110 .... .... .NBB]
                   |++- PRG/CHR A18..A17
                   ||+- 1=Lock outer bank register
                   |+-- 1=NROM-128 mode if N=1, 0=NROM-256 mode if N=1
                   +--- 1=NROM mode

NROM mode causes the VRC4's CPU A14 line to be held low, making the VRC4's two PRG registers apply to both $8000/$A000 and $C000/$E000. NROM-256 mode additionally replaces PRG A14 with CPU A14. The 'Lock' functionality is needed because the game that is active when PRG A17=1 (Crisis Force) uses 2 KiB of PRG-RAM that overlap the outer bank register.